Do you want to learn how to make potting mix at home? Want a quality potting mix recipe? Look no further! My early experiences with bagged potting mixes were not happy ones. With a sea of choices, clueless salespeople and confusing labels, I made more than one bad choice. Maybe you have too!
I fried my seedlings in what I thought from the label was ‘potting mix with fertiliser’ but was actually almost 100% fertiliser. I starved my plants with the next bag that didn’t have any food in it at all. Then another bag was virtually dead dirt that wouldn’t grow anything!
I got so seriously cheesed off wasting time and money with ‘dried arrangements‘ as a result. So I decided to make my own mix. It had to be better than going through all that pain!
Now, I try to be self-reliant and budget conscious where possible, by making my own supplies. If you don’t already, give home made potting mix a go. It’s easy, saves you money and a whole lot of headaches!
The ‘Dirt’ on Commercial and Soilless Potting Mixes
- Surprisingly, the old saying ‘You get what you pay for’ doesn’t always apply. You often take ‘pot’ luck! Gardening Australia ran some potting mix tests that proved this is the case. Even their seasoned experts were surprised by the results.
- Quality varies tremendously from certified organic products with strict standards to unlabelled contents of questionable origin and quality.
- Poor labelling leaves consumers in the dark.
- Peat and bark (commonly used ingredients) tend to become hydrophobic (water-repellent) as their moisture content drops to below 30%.
- May include chemical polymers in wetting agents to compensate for the ingredients that are often hard to wet.
On the up side, commercial mixes are sterile, disease free and very convenient as you just open the bag!
So Why Make Your Own Potting Mix?
- 1. SAVE MONEY. Potting mix bags range in price although high quality premium mixes are expensive. You can ALWAYS make your own premium quality potting mix cheaper!
- 2. CONVENIENCE. Making a batch and storing it saves time. This way, you always have some on hand for mini projects. You don’t have to make it from scratch every time. Make up just the quantity you need.
- 3. SAFE INGREDIENTS. Many non-certified organic commercial mixes contain water crystals or soil wetters. These are made from chemical polymers. After researching the dangers of these, I’ve decided not to use or recommend such products. Other bagged mixes contain chemical fertilizers. By making your own potting mix recipe, you know exactly what’s in it and can control the outcome you want with no hazardous ingredients.
- 4. SELF-RELIANCE. Making your own supplies is incredibly satisfying and you can share these skills with others.
- 5. LONGER LASTING. By choosing the right ingredients, you will get more mileage out of your own potting mix recipe, than a bagged mix based on bark. This ingredient quickly decomposes and becomes moisture resistant.
The Role of Potting Mix Ingredients
An ideal general potting mix should be:
- light and airy (so plants can easily take root and access oxygen in the soil);
- long-lasting (won’t break down or become compacted);
- moisture-retentive (hold water to save you money watering too frequently);
- and contain some nutrient value (save you fertilising too often).
Similarly, in your potting mix recipe, you need ingredients that provide different roles. These include drainage, aeration, water and nutrient retention, plant food, support, microbes and sometimes, thermal insulation.
Some ingredients perform multiple roles and I’ve chosen mine carefully to minimise cost and maximise the benefits. This mix is suitable for use in pots, hanging baskets and gardens.
Basic Potting Mix Recipe
I like to keep things simple. Whilst there’s no “one size fits all” potting mix recipe that is perfect for ALL plants, I believe every gardener should learn the basics to start with. When you’re confident after making a few potting mix batches, experiment! Try using more or less of the ingredients to suit your own needs. Or substitute with resources you have easy access to.
Potting Mix Recipe Materials
If you want to make your potting mix quickly, I suggest you have a ‘kit’ of basic supplies that you store together in your shed or storage area. Each time you need to make a batch, you will have it all together. A few good quality tools will last you for many years.
- a container for measuring;
- a large bucket for mixing in;
- access to water (kettle and hose/watering can);
- a small fork and trowel;
- a container for pre-soaking the coir peat; and
- your ingredients.
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When gardening, there are times when it’s important for your health, to wear protective safety equipment. This is not overkill! Legionnaires’ Disease is a risk factor when working with soils and potting mix.
These are simple precautions to take when making your own potting mix:
- To prevent inhaling dust or organic particles and the risk of any disease, wear a particulate face mask when working with organic materials.
- Wear suitable protective clothing and gloves. Wash your hands afterwards.
- Avoid making your potting mix on a windy day.
- Wear safety glasses to protect your eyes from dust.
- Use a spray bottle to mist water over dusty ingredients.
Potting Mix Recipe Ingredients
Ideally, source your ingredients from your own garden, locally and choose organic where possible. There are also many sustainable, low-cost options online. These are a few products that I’ve hand picked for quality, safety and value.
- 1 part pre-soaked Coir Peat. Coir peat bricks or coco husk is a cheap, but long lasting renewable resource. This is a more responsible environmental choice than peat moss. Coir peat is a waste by-product from the coconut-processing industry. The finer product left behind after the husk fibre is processed, is called ‘coconut coir’ or ‘coir peat.’ Don’t confuse this with peat moss, a very unsustainable resource!
- 1 part Vermiculite* (Grade 3 is a good size). Vermiculite is the silvery grey coloured particles you often see in potting mixes. It is a natural volcanic mineral that has been expanded with heat to increase its water holding capacity. It can come from a variety of sources around the world. You can also purchase asbestos-free vermiculite online.
- Vermiculite has a moderate CEC (cation exchange capacity). This means it can hold/make available minerals to the plants. It’s lightweight and inorganic. So it is a permanent ingredient that will not deteriorate or lose volume in the mix. Vermiculite is clean; odourless; non-toxic; sterile (no pathogens) and won’t become mouldy or rot. Depending on which brand you buy, the pH may be a little alkaline. [* If unavailable, use coarse sand – see Tips]
- 2 parts sieved Compost. Preferably home made, but a compost is an alternative if you haven’t got your own.
- 1/2 to 1 cup* Worm Castings or Vermicast (humus). Ideally you will have your own worm farm to add this perfect humus to your mix. Note: * this is an approximate quantity based on making 36 litres (4 x 9 litre buckets) of potting mix using a 9 litre brick of coir peat. Feel free to add more if you have it! If you can’t access vermicast, you can buy worm castings or use some humus from the bottom of your compost pile that is most decomposed or use good quality compost.
- A “part” can be whatever quantity you need: a small scoop or icecream tub; a 9 litre bucket or even a wheelbarrow depending on how much potting mix you require. I make 60 litres at a time in a large flexible bucket and store the rest till needed.
Potting Mix Recipe Method
STEP 1: Pre-soak coir peat in warm water in a large plastic container. Tip: To rehydrate a 9L block requires 4.5L of water so you need a container bigger than a 9L bucket to work in (minimum 14L size).
STEP 2: Mix equal quantities of pre-soaked coir peat and vermiculite (or coarse sand if using) together well in a large separate container.
STEP 3: Next, add the sieved compost and worm castings and combine thoroughly with (optional) nutrients.
STEP 4: Check the soil pH with a meter or pH testing soil kit. Most plants require a pH of between 6.0 and 7.0. If you are growing vegetables, from my experience, they grow best in the range of 6.2 – 6.8 pH.
TIP: Store in a container WITH a lid. This stops your potting mix drying out if not using it all immediately.
Check the Soil pH
Keep the potting mix moist and recheck the pH again a few days later. It should be neutral (around 7) or slightly acidic (6.2-6.8) for most plants.
Add Nutrients (optional but recommended!)
I suggest you also add minerals and slow release organic fertilisers. You can blend these additional ‘ingredients’ into the mix all at ONCE. Then all you have to do is plant and water! The plants have everything they need to start growing.
Want to Supercharge your Potting Mix?
Now you understand the basics. However, if you want to get the maximum out of your homemade potting mix, there’s so much more you can do. You will need to add other specific ingredients. These can help your plants take up nutrients faster, detoxify and insulate your soil against temperature extremes and help your potting soil mix last much longer.
After years of research, making tonnes of potting mix and testing to achieve the best results, I’ve created a one-of-a-kind ‘How to Make Potting Mix at Home Guide.‘ This laminated guide provides specific quantities of the ingredients that perform these roles (and explains the benefits of each) so you have the confidence of making a potting mix that is superior to just a basic one, within your own budget.
It also includes 5 DIY seed raising mix recipes. This guide also reveals what you need to add to adjust the pH level of your soil mix. CLICK HERE TO LEARN MORE. Read what people say about the guide here. CLICK HERE TO LEARN MORE.
This Potting Mix Guide provides you with many variations and options to make your own high quality potting mix, with no nasty chemical additives – and NO pine bark. It lists specific ingredients, their unique benefits and quantities and how to use them.
In this laminated double-sided Guide, I also reveal my five tried and tested organic seed raising mix recipes so you can boost your seed germination success.
CHECK IT OUT HERE and how it can help you. Hey, and if you’ve benefited by reading my article, I’d really appreciate you supporting my site. Thanks!
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My Potting Mix Recipe Tips
- I make my potting mix in a large flexible bucket with handles. It makes it easy to carry to the potting area or garden.
- If you want fast results, soak your coir peat bricks or coco husk in hot water to speed up hydration.
- Once you have potted up your plants, avoid letting the mix dry out. Coir peat holds moisture well, but if it really dries out over time, it can take time to re-wet thoroughly. Mulch really well.
- Compost breaks down as the nutrients are used up by the plants. So the volume of mix in your pot will gradually drop. You will need to top up with additional fresh potting mix around your plants over time.
- Some potting mix recipes suggest using perlite instead of vermiculite. However, I prefer not to use this due to the risk of silicosis. Overexposure to dust containing microscopic silica can cause scar tissue to form in the lungs, reducing the ability to extract oxygen from the air. It’s wise to always use a protective particulate face mask when using organic materials. Whatever products you use, please refer to the safety data sheet (SDS), material safety data sheet (MSDS), or product safety data sheet (PSDS) which will provides specific health and safety information.
- When buying a commercial potting mix, look for the Australian Standards Mark (AS 3743) on the packaging. A black tick indicates a basic potting mix and a red tick has added fertiliser which means it will feed your plant for a period of weeks. Alternatively, look for an equivalent quality guarantee in other countries.
- If I buy a bag of commercial potting mix or compost, I aim for a certified organic product with the BUD logo e.g. Searles.
So, that’s my take on potting mix! What recipes do YOU use if you make your own potting mix? I’d love you to share your thoughts here.
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